Electrode-joint compound



Patented Apr. 21, 1925.

IBETHUNE a. moon, or omcaeo, oomrm, or rmmmenm,

mors ,'assrqiion ro ALABAMA, aconrona'rronor warm r nosrnoiius anemone-coma: ooujroiiiin.

in Drawing. ori inal application filed Fovember a, a, Serial no. 421's, mime aj an app!!- To all-whom it may concern-f a it 4 Be it knoyvn that I, BETHUNE G. Knnen, a citizen of the United States of America, residing at Chicago, in the county-f Cook and State of Illinois, have. invented certain new and useful Improvements in Electrode- Joint Compounds, of which the following is a specification. I a s This invention relates to an improved joint compound for useinjoining the sections of electrodes as placed in service in an electric furnace, to improve such joints so as to ,give greater mechanical stren th and electrical conduc- 5 tivity to electro es at the joints with resulting increased length of service and greater economy in the electrode consumption of electric furnace operation.

The methods heretofore employed in making up the electrode joints, (ZODSlSt'iIl either depending upon the contact made by the faced ends of the electrodes when screwed together b the connecting pin, or of coating the t reads and faced ends with a paste made up of wholly or partly graphitized carbon, with some aqueo s binder consistingeither of water aloneor of a solution of molasses or other syrup of like nature. L 7

It is, however, well known to those exeriencedinthe use of electrodes in electric Furnace practice, that with the various sizes of the materials entering carbon electrodes, it is practically impossible to always machine threads and facesinvolved in the j oining-of electrodes that will give such an accurate and continuous contact throughout the joint as will even approximate in mechanical strength and electrical conductivity compound. Furthermore, the section of the electrode that is in the furnace is essentially at a high temperature from conducted heat and when a paste of conductive carbon with any aqueous syrup solution binder is applied to the upper end of such electrode While in service, the said binder material hardens and becomes immobile immediately thus defeating the object of the paste as a 5 medium for spreading over the surface and f completely filling all voids in the joint.

There appears further in' the melting of phosphatic materials in theelectric furnace to be some reaction of the gaseous and liquid and has for its object pockets,

a joint obtained by the use of some joint 150 centegrade.

muonmeaa 'ru 17, 1922. Serial No. 553,970.

materialsin the charge upon any joint compound of'a binder of a ueous-sugar solu- .l01'lS tor. the extent of e joint'being attacked on all of its contact surface, result ing in broken electrical. contact and 'resultant heating from resistance with often rup' tures said electrode at said; joint.

My invention has for its object" to produce an electrode joint tofore attained and itis based upon t lowing steps,,t'o-witf:- 7

1st: I select a paste of such character as to be softened by the heat at the joint, when made with an electrode in service; and which-will not therefore harden before it can flow into and completely fill all voids in the oint. Preferably the paste is composed e folsuperior to anyl hereof comminuted' electrically-.conductive car- 1 bon and a bituminous. binder thinly liquid in temperatures from 175 to 200 C. a

2nd: I avoid any tendency of'paste or generated gases being trapped in the inner end of the screw sockets and preventing the posltlve surface contact between the electrode ends, by the provision of vents lead ing from the inner ends of the screw seats and adapted to both vent the air or gen-- erated gases and to permit any excess paste n the screw joint to extrude. This feature 15 of great importance in that it avoids air prevents vany tendency of trapped paste in the seat to hold the electrode ends out of contact, and enables a thick paste to be employed with the assurance that it will fill all voids in joint.

3rd: I bake the joint before it assumes load bearing and current conducting functions. i a

In compounding and applying my improved. paste for electrode joints, I first make up a Easte consisting of either. amosphous grap ite or carbon largely raphi-. tized, and ground so that about fi ty per cent by weight thereof will pass a 200 sieve and al will pass a 100. mesh I'then mix with said carbon about vtwenty per cent of its wei ht of a mixture of tar and pitchpractical y free from napthalene. The said mixture vof tar and pitch should be in ratio of about one-third tar to twothirds pitch, and the tar must have been previously dehydrated, which dehydration can be performed by heating two hours at The tar and pitch mixture above described The paste above described works very successfully in the hereinafter described procedure, but I have further found that the joint made therewith is further improved by the addition of finely divided metal, preferably clean cast iron borings of not over 20 mesh size in proportion to about 15'per cent of the weight of the carbon, to the mixture and mixing all the constituents together at the temperature of 175 to 200 C.

This paste is applied to the electrode ends while hot, the temperature of such ends being maintained between 200 and 300 C. so that the paste above described will retain its plastic condition when applied and will remain so until the two sections of the electrodes to be joined are screwed together on the threaded pin to the full tension and face contact desired for the joint.

Ihave found that when the above described procedure is carried out joints are made that ave almost the electrical conductivity of the body of the electrode sebtions, and no attacking of the joints in the smelting 'of phosphatic materials is evident. This has been proven by, long comparative tests in the same furnace and under similar conditions with the result that the troubles with defective joints made up in accordance with my present method were practically nil as against almost continuous trouble from joints made up with pastes of carbon and aqueous solution binders as in the standard practice heretofore prevailing in the art.

While I have described the mixture and method used in very specific detail as to exact proportions and temperatures, which I have found to give the best results, it is obvious that the purpose of my invention is to produce a paste that will soften when heated and therefore can be spread freely so as to fill all voids in the joint and that will be of such character that when baked it will provide and maintain electrical conductivity and mechanical strength such as will approximate conditions obtaining in the body of the electrode section. It is therefore further obvious that with varying characteristics of available constituents for such a I nus-race paste, those skilled in the art may depart to be confined to the exact proportions and t details herein described.

. My present invention is a division of my application, Serial No. 421,944, filed on November 8th, 1920.

Though I have described with great particularity the details of the embodiment of the invention herein shown, it is not to be construed that I am limited thereto as changes in arrangement and substitution of equivalents may be made by those skilled in the art without departing from the invention as defined in the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. An electrode joint compound, composed of carbonaceous material, and a binder intimately mixed and of a character to become softened and brought into contact with a hot electrode in service to insure the necessary fluidity to completely fill all voids in the joint between the hot electrode section and the section to be joined thereto.

2. An electrode joint compound, composed ofcomminuted carbonaceous material mixed with a bituminous binder which becomes softened and brought into contact with a hot electrode in service to insure the necessary fluidity to completely fill all voids in the joint between the hot electrode section and the section to be joined thereto.

3. An electrode joint compound, composed of comminuted. carbonaceous material mixed withia binder of pitch and dehydrated tar thinly liquid at 175 C. to 200 C.

4. An electrode joint compound, composed of ,comminuted graphitized carbon intimately mixed with pitch and tar, said pitch and tar mixture being fluid at temperatures ranging between 170 degrees to 200 degrees 0., and said resulting mixture of all constituents being of such proportions that its physical state is that of a stiff paste at a temperature of 175 degrees C.

5. An electrode joint compound, composed of comminutedgraphitized carbon, metal, and a bituminousbinder.

In testimony whereof I affix my signature.

BETHUNE G. KLUGH.

Witness:

NoMmWErsH. 

